Reduction of in-stent restenosis risk on nickel-free stainless steel by regulating cell apoptosis and cell cycle

One-Year Outcomes of CGuard Double Mesh Stent in Carotid Artery Disease: A Systematic Review and Meta-Analysis

Background: Prospective single and multicenter studies have shown improved outcomes of patients who underwent carotid artery stenting with the novel CGuard dual-layer mesh stent at 1 year. Objectives: The aim of this study is to conduct a systematic review and meta-analysis of all published studies to assess 1-year efficacy and outcomes of CGuard in patients with carotid stenting. Methods: A systematic search was performed. All studies enrolling at least 20 patients were included in our analysis. The primary endpoints were death (all-cause, cardiovascular and ipsilateral stroke-related death) and stroke rate at 1 year. The secondary endpoint was in-stent restenosis at 1 year. Results: The final analysis included 1709 patients. The one-year all-cause mortality rate was 2.97% (39/1699, 95% CI: 1.26-6.86%, I2 = 67%, t2 = 0.3442, p < 0.01), cardiovascular-related death was 0.92% (10/1616, 95% CI: 0.35-2.39%, I2 = 34%, t2 = 0.2302, p = 0.18), and ipsilateral stroke-related death was 0.3% (1/1649, 95% CI: 0.1-0.87%, I2 = 0%, t2 = 0, p = 0.69). The one-year ipsilateral stroke rate was 1.21% (16/1649, 95% CI: 0.58-2.5%, I2 = 28%, t2 = 0.1433, p = 0.23), transient ischemic attacks (TIAs) rate was 1.78% (19/1149, 95% CI: 1.11-2.84%, I2 = 0%, t2 = 0, p = 0.69), and total composite 1-year stroke/TIA rate was 2.97% (32/1149, 95% CI: 1.84-4.77%, I2 = 0%, t2 = 0, p = 0.41). The in-stent restenosis rate at 1 year was 1.06% (13/1653, 95% CI: 0.48-2.34%, I2 = 28%, t2 = 0.2308, p = 0.22). Conclusions: This meta-analysis shows that CAS with CGuard is safe with minimal neurological adverse events and in-stent restenosis rate at 1 year.

Anti-inflammatory Effect of (-)-Epigallocatechin-3-O-gallate on Human Umbilical Vein Endothelial Cells Grown on 316L Stainless Steel via STAT3/NF-κB Signaling

Stainless steel (316L SS) is commonly used to build coronary artery stents for the treatment of occluded arteries. However, tissues in contact with the stent may develop inflammation that can lead to restenosis. The natural substances derived from normal diet provide a pool of candidates that have potential to treat cardiovascular diseases. (-)-Epigallocatechin-3- O-gallate (EGCG), a polyphenolic flavonoid present in green tea, has antioxidant, antithrombogenic, and anti-inflammatory effects, and may reduce the risk of cardiovascular diseases. This study aimed to investigate whether EGCG has an anti-inflammatory effect on human umbilical vein endothelial cells (HUVECs) attached to the surface of 316L SS. We evaluated cell proliferation using the dimethyl thiazolyl tetrazolium bromide method in HUVECs after treatment with EGCG. Enzyme-linked immunosorbent assay (ELISA) assessed the level of inflammatory cytokines, including interleukin 6 (IL-6) and tumor necrosis factor (TNF) in HUVECs. We further investigated the regulatory mechanisms of the signal transducer and activator of transcription 3 (STAT3)/NF-κB signaling pathway in HUVECs by Western-blot analysis. We found that HUVECs cultured on 316L SS had increased cell proliferation and inflammation, and these can be inhibited by treatment with EGCG. EGCG reduced the secretion of IL-6 and TNF and decreased the expression of STAT3 and NF-κB in HUVECs cultured on 316L SS. Consequently, our study demonstrated that EGCG treatment ameliorates the proliferation of HUVEC when cultured with 316L SS, potentially by modulating the inflammation responses via the STAT3/NF-κB signaling pathways.

Endothelial Autophagy in Coronary Microvascular Dysfunction and Cardiovascular Disease

Coronary microvascular dysfunction (CMD) refers to a subset of structural and/or functional disorders of coronary microcirculation that lead to impaired coronary blood flow and eventually myocardial ischemia. Amid the growing knowledge of the pathophysiological mechanisms and the development of advanced tools for assessment, CMD has emerged as a prevalent cause of a broad spectrum of cardiovascular diseases (CVDs), including obstructive and nonobstructive coronary artery disease, diabetic cardiomyopathy, and heart failure with preserved ejection fraction. Of note, the endothelium exerts vital functions in regulating coronary microvascular and cardiac function. Importantly, insufficient or uncontrolled activation of endothelial autophagy facilitates the pathogenesis of CMD in diverse CVDs. Here, we review the progress in understanding the pathophysiological mechanisms of autophagy in coronary endothelial cells and discuss their potential role in CMD and CVDs.

Effect of Copper-Containing Stainless Steel on Apoptosis of Coronary Artery Smooth Muscle Cells

Background:

We aimed to investigate the effect of copper stainless steel on apoptosis of vascular smooth muscle cells in coronary artery.

Methods:

The study was carried out in 2019 at Hubei University of Medicine, Xiangyang, China. The rat coronary artery smooth muscle cell was used for cell resuscitation and culture. MTT method was used to visualize cell growth curve and to detect the cell survival and growth. The incubated cells were randomly divided into copper-containing stainless-steel group, ordinary stainless-steel group, and control group. The cells were made into single cell suspension, which were intervened by experimental group and incubated in incubator with CO2 for 48 hours. TUNEL method was used to detect the apoptosis. The number of apoptotic cells in five high power fields (×200) was counted. The expression of Fas protein in three groups of cells was detected by Western blot.

Results:

The growth curves of rat coronary artery smooth muscle cells showed that the OD value of the cells reached the plateau 7 days after inoculation, indicating that the cells grew well. TUNEL staining showed the apoptosis in all three groups. The apoptotic index in copper-containing group was significantly higher than that in common stainless-steel group (P <0.01). The results of the Fas protein expression level through Western blot showed that the level in the copper-containing group was significantly higher than that in the common stainless-steel group (P<0.01).

Conclusion:

Copper-containing stainless steel can promote apoptosis of coronary artery smooth muscle cells. The material could prevent stent restenosis.

EGCG Regulates Cell Apoptosis of Human Umbilical Vein Endothelial Cells Grown on 316L Stainless Steel for Stent Implantation

Background

Nowadays, medical grade 316L stainless steel (316L SS) is being widely used for intravascular stents, and the drug-eluting stent (DES) system is able to significantly reduce the occurrences of in-stent restenosis. But the drugs and the polymer coating used in DES potentially induce the forming of late stent thrombosis. In order to reduce the occurrence of ISR after stent implantation, the development of novel drugs for DESs is urgently needed.

Methods

This study aimed to investigate the potential mechanisms of epigallocatechin-3-gallate (EGCG) on human umbilical vein endothelial cells (HUVEC) grown on 316L stainless steel (316L SS) using flow cytometry and Q-PCR methods.

Results

Our results showed that EGCG (12.5, 25, 50, 100 μmol/L) significantly inhibited HUVEC proliferation. Flow cytometry analysis indicated that EGCG (25, 50, 100 μmol/L) induced apoptosis. Moreover, qRT-PCRrevealed that genes associated with cell apoptosis (caspase-3, 8, 9, Fas) and autophagy (Atg 5, Atg 7, Atg 12) were up-regulated after EGCG treatment.

Conclusion

These findings indicate that EGCG possesses chemo preventive potential in stent coating which may serve as a novel new drug for stent implantation.

Designing Better Cardiovascular Stent Materials - A Learning Curve

Cardiovascular stents are life-saving devices and one of the top 10 medical breakthroughs of the 21st century. Decades of research and clinical trials have taught us about the effects of material (metal or polymer), design (geometry, strut thickness, and the number of connectors), and drug-elution on vasculature mechanics, hemocompatibility, biocompatibility, and patient health. Recently developed novel bioresorbable stents are intended to overcome common issues of chronic inflammation, in-stent restenosis, and stent thrombosis associated with permanent stents, but there is still much to learn. Increased knowledge and advanced methods in material processing have led to new stent formulations aimed at improving the performance of their predecessors but often comes with potential tradeoffs. This review aims to discuss the advantages and disadvantages of stent material interactions with the host within five areas of contrasting characteristics, such as 1) metal or polymer, 2) bioresorbable or permanent, 3) drug elution or no drug elution, 4) bare or surface-modified, and 5) self-expanding or balloon-expanding perspectives, as they relate to pre-clinical and clinical outcomes and concludes with directions for future studies.

In vivo and in vitro analyses of the effects of a novel high-nitrogen low-nickel coronary stent on reducing in-stent restenosis

Currently, percutaneous coronary intervention is an important treatment for coronary heart disease. However, the in-stent restenosis rate is still approximately 10–30% after stenting. Nickel ions from the stent are considered to be associated with in-stent restenosis. Therefore, in the present study, we quantitatively evaluated in-stent restenosis after implanting the novel high-nitrogen low-nickel coronary stent (HNS) and studied the mechanism underlying the reduction in in-stent restenosis by using ELISA and Western blot. The in vivo results showed that the HNS could significantly reduce neointima formation and inflammation as compared to SUS316L stents (316L) at 180 days after implantation in porcine coronary arteries and that vascular endothelial growth factor-A expression in porcine coronary arteries after HNS implantation also decreased. The in vitro results showed that, in the case of the HNS, human umbilical vein endothelial cell (HUVEC) proliferation was lower and lesser IL-6 release was noted from HUVECs at one and three days after culture than in the 316L group. Furthermore, p-STAT3 expression in HUVECs on the HNS surface was downregulated after culture for seven days. Thus, we conclude that the HNS could be a promising alternative coronary stent for percutaneous coronary intervention.

Stable Titania Nanostructures on Stainless Steel Coronary Stent Surface for Enhanced Corrosion Resistance and Endothelialization

Stainless steel (SS) coronary stents continue to present risk of in-stent restenosis that impact its long term safety and efficacy. The present work focuses on developing a drug-free and polymer-less surface on coronary stents by utilizing a titania (TiO₂ ) nanotexturing approach through hydrothermal processing, that will offer improved stent performance in vivo. Mechanically stable and durable nanotextured coatings are obtained on SS stents that also offer good corrosion resistance. In vitro vascular cell (endothelial and smooth muscle cells) studies on surface modified SS show preferential rapid endothelialization with enhanced nitric oxide production and reduce smooth muscle cell proliferation, in comparison to unmodified SS. In vivo evaluation of the nanotextured stents after subcutaneous implantation in rabbits show reduced irritability and minimal localized inflammatory response. These beneficial effects suggest that the stable, easily scalable titania nanosurface modification strategy on coronary stent surfaces can be a much cheaper alternative to drug eluting stents in addressing in-stent restenosis.

Antibacterial abilities and biocompatibilities of Ti-Ag alloys with nanotubular coatings

Purpose

To endow implants with both short- and long-term antibacterial activities without impairing their biocompatibility, novel Ti–Ag alloy substrates with different proportions of Ag (1, 2, and 4 wt% Ag) were generated with nanotubular coverings (TiAg-NT).

Methods

Unlike commercial pure Ti and titania nanotube, the TiAg-NT samples exhibited short-term antibacterial activity against Staphylococcus aureus (S. aureus), as confirmed by scanning electron microscopy and double staining with SYTO 9 and propidium iodide. A film applicator coating assay and a zone of inhibition assay were performed to investigate the long-term antibacterial activities of the samples. The cellular viability and cytotoxicity were evaluated through a Cell Counting Kit-8 assay. Annexin V-FITC/propidium iodide double staining was used to assess the level of MG63 cell apoptosis on each sample.

Results

All of the TiAg-NT samples, particularly the nanotube-coated Ti–Ag alloy with 2 wt% Ag (Ti2%Ag-NT), could effectively inhibit bacterial adhesion and kill the majority of adhered S. aureus on the first day of culture. Additionally, the excellent antibacterial abilities exhibited by the TiAg-NT samples were sustained for at least 30 days. Although Ti2%Ag-NT had less biocompatibility than titania nanotube, its performance was satisfactory, as demonstrated by the higher cellular viability and lower cell apoptosis rate obtained with it compared with those achieved with commercial pure Ti. The Ti1%Ag-NT and Ti4%Ag-NT samples did not yield good cell viability.

Conclusion

This study indicates that the TiAg-NT samples can prevent biofilm formation and maintain their antibacterial ability for at least 1 month. Ti2%Ag-NT exhibited better antibacterial ability and biocompatibility than commercial pure Ti, which could be attributed to the synergistic effect of the presence of Ag (2 wt%) and the morphology of the nanotubes. Ti2%Ag-NT may offer a potential implant material that is capable of preventing implant-related infection.

Biological behaviour of human umbilical artery smooth muscle cell grown on nickel-free and nickel-containing stainless steel for stent implantation

To evaluate the clinical potential of high nitrogen nickel-free austenitic stainless steel (HNNF SS), we have compared the cellular and molecular responses of human umbilical artery smooth muscle cells (HUASMCs) to HNNF SS and 316L SS (nickel-containing austenitic 316L stainless steel). CCK-8 analysis and flow cytometric analysis were used to assess the cellular responses (proliferation, apoptosis, and cell cycle), and quantitative real-time PCR (qRT-PCR) was used to analyze the gene expression profiles of HUASMCs exposed to HNNF SS and 316L SS, respectively. CCK-8 analysis demonstrated that HUASMCs cultured on HNNF SS proliferated more slowly than those on 316L SS. Flow cytometric analysis revealed that HNNF SS could activate more cellular apoptosis. The qRT-PCR results showed that the genes regulating cell apoptosis and autophagy were up-regulated on HNNF SS. Thus, HNNF SS could reduce the HUASMC proliferation in comparison to 316L SS. The findings furnish valuable information for developing new biomedical materials for stent implantation.

The development of carotid stent material

Endovascular angioplasty with stenting is a promising option for treating carotid artery stenosis. There exist a rapidly increasing number of different stent types with different materials. The bare-metal stent is the most commonly used stent with acceptable results, but it leaves us with the problems of thrombosis and restenosis. The drug-eluting stent is a breakthrough as it has the ability to reduce the restenosis rate, but the problem of late thrombosis still has to be addressed. The biodegradable stent disappears after having served its function. However, restenosis and degradation rates remain to be studied. In this article, we review every stent material with its characteristics, clinical results and complications and point out the standards of an ideal carotid stent.

Study of biocompatibility of medical grade high nitrogen nickel-free austenitic stainless steel in vitro

Adverse effects of nickel ions being released into the living organism have resulted in development of high nitrogen nickel-free austenitic stainless steels for medical applications. Nitrogen not only replaces nickel for austenitic structure stability but also improves steel properties. The cell cytocompatibility, blood compatibility and cell response of high nitrogen nickel-free austenitic stainless steel were studied in vitro. The mechanical properties and microstructure of this stainless steel were compared to the currently used 316L stainless steel. It was shown that the new steel material had comparable basic mechanical properties to 316L stainless steel and preserved the single austenite organization. The cell toxicity test showed no significant toxic side effects for MC3T3-E1 cells compared to nitinol alloy. Cell adhesion testing showed that the number of MC3T3-E1 cells was more than that on nitinol alloy and the cells grew in good condition. The hemolysis rate was lower than the national standard of 5% without influence on platelets. The total intracellular protein content and ALP activity and quantification of mineralization showed good cell response. We conclude that the high nitrogen nickel-free austenitic stainless steel is a promising new biomedical material for coronary stent development.